At least three Iranian policemen have been killed and several more were wounded during a protest in Tehran, where members of a religious sect gathered around a police station to demand the release of one of their order.

The incident took place on Pasdaran Street in northern Tehran. Unverified footage from the scene has been circulating on social media. One video appears to show firebombs being thrown as police fight with protesters, while another appears to show a white bus plowing into a crowd of riot officers.

BREAKING: #Iran's Islamic regime Police has directly shot at #Darvish minority members who were peacefully protesting arrest of the group members in #Tehran. Three of protesters are shot at face and head by shotgun. This has made #Darvish members angry, they are now fighting back pic.twitter.com/tVVnzwj8bD

BREAKING: This is second video shows #Darvish protesters retaliated death of their members & attacked #Iran's Islamic regime security forces who were trying to arrest their 90 years old leader. They used a bus & have killed at-least three security forces in Pasdaran, #Tehran. pic.twitter.com/RFQdU31PP5

Additional footage from the scene also shows officers in riot gear running down the street after apparently being attacked by protesters.

#Breaking: at least 3 police officers were killed, some others injured when a bus ploughed into anti-riot forces during a clash with Gonabadi Darwishs (a sufi-like cult) who were attacking police with cocktails and machetes over the arrest of one their members.Fars pic.twitter.com/vRWKDHRqLp

The protesters were dervishes from the Sufi order of Gonabadi. Opposition activists and supporters of the dervish shared images of bloodied protesters, claiming that they were attacked by the security forces first and one of the protesters had been shot.

These are the #Darvish protesters who police force of #Iran's Islamic regime had used shotgun to fire at their peaceful protest in #Tehran few hours ago. Now in retaliation, they used a bus to fight back the Police & #Basij militia who were trying to arrest #Darvish's leader. pic.twitter.com/ESc1RdnGmO

According to Reuters, a police spokesman revealed on state TV that: "Some disruptors of security and order used a bus today and killed three police officers." "The murderers were arrested seconds after their crime," the spokesman added. Ten people were immediately arrested at the scene and the area has now been sealed off by the security forces.

In Sufism, dervishes are known for their vows of poverty and austerity, as well as the trance-like dances in their rituals. Some human rights and activist groups have alleged that dervishes face persecution in Iran. In January, 10 members of the Sufi order were injured and three more were arrested during a protest in Fars province, also over the arrest of one of their leaders.